May 21 2020, Adobe released an update to Acrobat Reader, which addresses problems that have recently affected reading the videos in PDFs, including our ebooks.
PLEASE UPDATE Adobe Acrobat Reader to version 20.009.20065.
If you are on Windows 10, you need to take the following steps to see the videos using Adobe Acrobat Reader: Open Reader and navigate to Edit>Preferences. In Preferences select 3D and Multimedia, then tick the boxes for Use Flash Player, and Enable 3D Content. Close the app and re-open it and now go to File>Open and navigate to where your Vivebooks pdf is stored. When you open the file, you will get a pop-up that tells you that support for Flash is being discontinued at the end of 2020 and invites you to turn Flash off the next time you launch. DON’T! This is the only way Adobe will play multimedia in PDFs for the moment. Adobe has confirmed that are working on a new standard that will play video without Flash but it isn’t ready yet . . .